The field of the invention is nursing bottles and the invention relates more particularly to nursing bottles which prevent the buildup of a negative pressure within the bottle.
Many attempts have been made to provide a nursing bottle which has some means for air to enter the interior of the bottle as it is being used. Various constructions are shown in the various U.S. Pat. Nos. 1,972,895; 2,094,721; 2,394,722; 3,200,980; 3,292,808; 3,768,683; 4,010,861; 4,401,224; 4,545,491; 4,685,577; 4,723,668; and French Pat. No. 1,058,610. Two major shortcomings occur with the constructions shown in the above-listed patents. First is the difficulty of cleaning the device in that the devices invariably have small orifices or cracks which can trap milk and which, if not carefully cleaned, can result in pockets of bacteria. Secondly, the constructions are inherently expensive.
The large number of attempts to solve this problem shows a recognition of the problem caused by a negative pressure within the bottle which leads to bubbles and discomfort for the baby. Also, the device should facilitate the cleaning of the bottle rather than providing a source of bacterial contamination.